First love came back into my life?

My first love came back in to my life recently. We have known each other for over a decade He was my first love but we were so young that we drifted apart for awhile throught the years. Eventually, He became an addict and was in and out of rehabs. Finally, recently he got completely sober and is doing really good and decided to contact me. At first I was scared because so much time has past and we live two completely different lifestyles but something in me told me to meet up with him.

When we first met up last month, It was like we went back in time and picked up right where we left off I never had so much fun and old feelings that I thought were long gone came rushing back to me. I felt alive again and apart of me that died along time ago awoken.

I see him at least once a week and we have been "hooking up" also I think he knows and I both know we could never be in a relationship again. He also told me that he is slowly starting to talk to one of his ex's. When he told me that I got really bothered by it because I really do care about him and I would love to be with him but it could just never be.

I know to keep seeing him will only make me grow stronger feelings and eventually lead to turmoll. But I dont want him out of my life. My feelings are all so mixed up I dont know what to do?